The present invention relates to a semiconductor device configuration, and more particularly to a semiconductor device design in which the functionality of a channel stop and a body contact are realized by a single structure.
Metal oxide semiconductor (MOS) transistor designs require a structure to prevent leakage currents between unrelated regions or devices in the circuit, and also require a structure to electrically contact the body of the MOS transistor. With respect to the former, high operational voltages of MOS transistors in current designs often require the use of high resistivity silicon. A consequence of using high resistivity silicon is that the metal and polysilicon interconnects used in the transistors can cause the surface of the silicon to invert polarity (change from N type to P type, or vice versa). This can cause unwanted communication between different nodes in a circuit. Operating voltages above the inversion voltage often occur in high voltage circuits and applications, creating a need to form isolation features that prevent inversion of the silicon. With respect to the latter, many MOS circuit designs require a connection of the source terminal of a MOS transistor to the body region of the MOS transistor in order to control the body potential so that stable and reliable operation can be ensured.
Unwanted inversion and communication between different nodes in a circuit have been addressed in the prior art through the use of diffused or implanted channel stops, trench isolation or polysilicon field plates.